(Noun) 1. A person who is on the apposing side. 2. A person who doesn't have enough of ones trust to be granted friendship. 3. Borderline enemy. (enemy, foe, Acquaintance)

A Friendo for example might be an acquaintance - who seems untrustworthy or unreliable. Someone who is sneaky, a snitch, or a back stabber. A friendo might be an old friend who has terminated friendship through disloyal activity.